Quote Originally Posted by liza View Post
Do shifters really make a bigger difference than derailleurs? I thought it was the other way around. Why do the levers make so much difference? (I'm asking this sincerely -- I really didn't know).
Different levels of shifters can have different mechanical design. The throw to shift can be shorter/longer and pressure needed can be lighter/heavier. The shape of the hood can be vastly different.

I have heard that DA shifters require a very light touch to shift compared to Ultegra and I have seen that the DA hoods are narrower. Both of these being great for small hands. I don't know how Ultegra compares to 105.